ICS843021I-01 Datasheet, PDF (9/15 Pages) Integrated Circuit Systems – FEMTOCLOCKS-TM CRYSTAL-TO-3.3V, 2.5V 125MHZ LVPECL CLOCK GENERATOR

ICS843021I-01
FEMTOCLOCKS™CRYSTAL-TO-3.3V, 2.5V LVPECL CLOCK GENERATOR
Termination for 2.5V LVPECL Outputs
Figure 4A and Figure 5B show examples of termination for 2.5V
LVPECL driver. These terminations are equivalent to terminating
50Ω to V_CC – 2V. For V_CC= 2.5V, the V_CC– 2V is very close to
ground level. The R3 in Figure 4B can be eliminated and the
termination is shown in Figure 4C.
V_CC = 2.5V
50Ω
50Ω
2.5V LVPECL Driver
2.5V
R1
R3
250
250
2.5V
+
–
R2
R4
62.5
62.5
V_CC = 2.5V
50Ω
50Ω
2.5V LVPECL Driver
2.5V
+
–
R1
R2
50
50
R3
18
Figure 4A. 2.5V LVPECL Driver Termination Example
Figure 4B. 2.5V LVPECL Driver Termination Example
VCC = 2.5V
50Ω
50Ω
2.5V LVPECL Driver
2.5V
+
–
R1
R2
50
50
Figure 4C. 2.5V LVPECL Driver Termination Example
IDT™ / ICS™ 3.3V , 2.5V LVPECL CLOCK GENERATOR
9
ICS843021AGI-01 REV. A DECEMBER 3, 2007